Portable fan-type air heater



April 22, 1952 J. F. VOLKER 2,594,101

PORTABLE FAN-TYPE AIR HEATER Filed July 7, 1950 3 Sheets-Sheet 1 Fig.l. 28

INVENTOR John F. Volker.

ATTORNEY WITNESSES:

April 22, 1952 J. F. VOLKER 2,594,101

PORTABLE FAN-TYPE AIR HEATER Filed July '7, 1950 3 Sheets-Sheet 2 W TNESSES: @w

INVENTOR John F. Volker.

ATTORNEY April 22, 1952 J. F. VOLKER PORTABLE FAN-TYPE AIR HEATER 3 Sheets-Sheet 3 Filed July '7, 1950 Fig. l0.

INVENTOR John F. Volker. BY

WITNESSES:

ATTORNEY Patented Apr. 22, 1952 PORTABLE FAN-TYPE AIR HEATER John F. Volker, Meadville, Pa., assignor to West-- inghouse Electric Corporation, East Pittsburgh, 1%., acorporation of Pennsylvania Application July 7, 1950, Serial No. 172,549

6 Claims. (01. 219 39) This invention is directed to improvements in portable fan-type air-heaters for use in any convenient place.

An object of my invention is to provide a fan-type air-heater that is small, compact, efficient, and of comparatively low cost.

An important object of my invention is to provide a fan-type air-heater of a portable nature that has an outer casing, or shell, that always remains cool, that is, at or close to room temperature. In the preferred manner of accomplishing this object, parts of the air-heater are so constructed and arranged that some of the cool air that passes into the air-heater for heating, first moves in contact with the inside of the outer shell before it reaches the heating means of the heater.

A feature of my invention resides in the arrangement of a thermostat therewith which responds jointly to the temperature of the cool incoming air and the temperature of the heating means.

A further object of my invention is to provide an air-heater of a type described which uses embedded heating elements such as are now used in electric ranges and the like.

Another feature of my invention resides in the construction of the air-heater so that either one or more heating elements of the type mentioned may be used therewith; and when more than one are used, the heating elements can be alike and shaped so that they can be compactly arranged to occupy a minimum of space. Consequently a minimum number of parts are required to produce differently rated portable fantype air-heaters of the type described.

Objects, features and innovations of my invention, in addition to the foregoing, will be discernible from the following description. This description is to be taken in conjunction with the accompanying drawings which are deliberately limited to such details as are adequate for an understanding of my invention. In the drawings,

Figure 1 is a vertical axial sectional view of an air-heater embodying my invention;

Fig. 2 is a rear view thereof with parts broken away;

Fig. 3 is a front view thereofwith parts broken away;

Fig. 4 is a sectional view substantially on the line IV-IV of Fig. 1, with parts removed;

Fig. 5 is a front view of the front heating element;

Figs. 6 and 7 are a top view and a side view, respectively, of the heating element of Fig.5;

Fig. 12 is a modified fragmentary front view of a modified front end of the air-heater; and

Fig. 13 is a schematic diagram of electric-wiring utilizable with the air-heater.

Referring to the drawings, a portable air-heater in accordance with my invention comprises a base.

2 to which a yoke 4 is secured; the yoke carrying. through bolt and nut means 6, an outer metallic casing or shell 8 in the form of an axially straight.

tubular member 8 which is preferably a sheet metal tube circular in cross-section. A handle in is secured to the top of the outer shell 8 so that the air-heater can be conveniently carried to any place where it is to be used.

The back or air inlet side of the air-heater comprises a rear guard ring 12 and an air inlet grill !4 having diamond-shaped openings. The grill I4 is secured to the guard ring l2 preferably by tack welding; and the guard ring I2 is removably secured to the back end of the outer shell 8 by a plurality of circumferentially distributed screws IS.

The front or air outlet side of the air-heater is formed by a front sub-assembly which is removably secured to the front end of the outer shell 8 by a plurality of circumferentially distributed screws. The front sub-assembly comprises a sheet metal guard ring l8, air outlet metal grill 20 having diamond-shaped openings, a sheetmetal inner shell 22, and heating meansindi cated in its entirety by the reference numeral 24. The inner shell 22 is also in the form of tube that is straight sided axially and circular in crosssection.

As shown in Fig. 1, the guard ring 20 and the inner shell 22 have abutting circular portions or flanges 25, 28 and 30, respectively. In making the sub-assembly, the guard ring 18, grill 20 and inner shell 22 may be placed in the jig and their abutting portions 26, 28 and 30 tack welded with the inner shell portion 30 on the inside and the guard ring flange 26 on the outside. I have found that tack welding these parts at a plurality of about eight points'around their circumferences holds them securely and also distorts the abutting portions to a sufiicient extent to provide intake air openings therebetween outwardly of the inner shell 22. Such anopening is shown exaggerated at 32 in Fig. 3.

l8, the grill The heating means 24 of the front sub-assembly is carried inside the inner shell 22 near the front grill 2a. The heating means comprises one or more spirally wound heating elements. In the embodiment shown, two such heating elements 32 and 36 are provided. The heating elements are constructed in the same way, and each is made by forming a common type of resistor rod to the proper shape. Such a resistor rod usually comprises an outer metal tube 38 of copper, an inner resistor wire 46 and granular insulating material 42, comprising for example, magnesium oxide, compacted between the resistor wire ti! and the outer tube 38. A suitable length of such a heating element is provided with enlarged terminal ends and shaped to a spiral such as shown in Figs. and 9. Preferably, in accordance with my invention, the heating rod is flattened prior to being formed in a spiral, so that the heating rod is oval in cross section. When wound the flattened portions face each other.

As shown in Fig. 5, the front heating element 34 comprises a terminal end as in the plane of the spiral, and 'a longer terminal end 26' that bends axially away from the center of the spiral and then extends in a direction parallel to the other terminal end 44 so as to provide end tips which are substantially on the same level but slightly ofiset.

For carrying this heating element 34 from the inner shell 22, the inner shell is provided with a hole which is completely covered by a suitably perforated curved mounting plate at of sheet metal. The terminal ends 14 and 46 of the heating element 34 extend through this mounting plate, as shown in Fig. l. The outer heating element can be silver soldered to the curved mounting plate 28 in a manner to provide protruding ends of the resistor wire for receiving energizing conductors. I

The back heating element 38 has the same construction as the front heating element 34, and comprises a short terminal end 5a in the plane of its spiral and a longer terminal end 52 bent away from the center of the spiral and extending upwardly substantially parallel to the terminal end 50 but offset therefrom. This heating element 36 is also carried by the mounting plate 48, but before this heating element is secured to the mounting plate, it is rotated 186 Consequently, its terabout a vertical axis. minal 50 will be adjacent the terminal end it of the heating element 32, and the terminal end 52 of the heating element 35 will be adjacent the terminal end 44 of the heating element This places the longer terminal ends 25 and 52 substantially in a plane parallel to the planes of thespirals of the heating elements as and 36, and substantially midway therebetween. As a result an extremely compact arrangement is obtained for the heating elements.

In the preferred embodiment, the two heating elements are connected together electrically in parallel; and to this end, energizing conductors 52 and 56 are provided. The energizing conductor" 5 1 can intimately be soldered to the ends of the protruding resistor wires 46 of the terminal ends it and 5G, and the energizing conductor 56 can similarly be connected to the protruding ends of the resistor wires 29 of the terminal ends 44 and 52.

For forcing air horizontally past the heating means 24, a fan 68 is carried by a mounting bracket 62 secured to the outershell 8. The fan 60 comprises a propeller 64 and a driving motor 6B. The motor preferably has radiating fins over which air to be heated sweeps. The bracket 62 is so arranged that the propeller 64 is just inside the back end of the inner shell 22.

The propeller is of the axial flow type. When the motor 66 is energized, the propeller draws cool air through the rear grill I i and forces it through the openings in the oppositely turned, spirally wound heating elements 34 and 36 and then outwardly'through the front grill 29. Accordingly, the air-heater can be said to have a first or main air passage that extends from the air inlet grill I4, through the inside of the inner shell 22 and through the air outlet grill 20. This flowing air provides an injector action that draws additional cool secondary air through the aforesaid openings 32 at the abutting joints of the sub-assembly formed by the flange portions 26, 28 and 30, respectively. This air flows generally as indicated by the arrows A through the annular space between the inner shell 22 and the outer shell 8. Accordingly, the inner and outershells 8 and 22 form a second air passage which is on the outside of the afore-described inner main air passage. Secondary air flows through this outside air passage in a direction opposite to that in which the air flows through the inner main passage, the secondary air turning around the back edge of the inner shell 22 and merging into the air driven through the heating means 24 by the propeller 64. The openings 32 at the joining flanges of the front sub-assembly form an inlet for the outer or second air passage,.

the outlet of which is at the back edge of the inner shell 22 where the secondary air-stream merges into the main airstream flowing into the inner air passage.

The secondary air in the outer air passage is substantially at room temperature and keeps the outer shell 8 cool. The inner shell 22 also keeps radiant heat from the heating means 22 from impinging on the outer shell 8. Consequently, the outer shell 8 can be safely touched during operation of the air-heater.

Preferably, an adjustable thermostat control is built into the air-heater. This thermostat control comprises a thermostat 58 that may be carried by the inner shell 22 at a point radially outward from the heating 'means 24 so that the thermostat is subjected to the temperature of the incoming air passing through the second air passage and to heat of the inner shell 22 supplied by the heating means 22. Should the incoming air be hotter than usual, this thermostat can turn off the energy to'the heater sooner than it would otherwise.

In the event that the openings 32 at the flange joints of the front sub-assembly are inadequate in area for a suiilcient supply of secondary air, the front guard ring 18 can be provided with a plurality of circumferentially spaced inlet openings in the form of holes it, as shown in Fig. 12.

The electric circuit in the air-heater may take any suitable form. As shown for example in Fig. 13, power conductors 22 are connected to a main control switch E i. Power is delivered to the heating elements 32 and 36 in parallel by a circuit E6, the parallel circuit branch being in series.

heating means is also energized. Preferably both switches are mounted on the air-heater, and the power conductors i2 constitute the conventional cord that terminates in a plug for the conventional receptacle.

While I have described my invention in such detail as is believed adequate foriliustrating the best mode now contemplated by me to one skilled in the art, it is obvious that the principles of my invention are subject to modification and can find expression in other embodiments of fantype air-heaters.

I claim as my invention:

1. A portable fan-type air-heater comprising a shell means having a first air inlet, a first air outlet and a first air passage between said air inlet and air outlet, heating means in said first air passage, said shell means having a second air inlet and a second air outlet and a second air passage therebetween, said second air passage being on the outside of said first air passage, said second air outlet merging into said first air passage at a point between said first air inlet and said first air outlet, a fan comprising an axial flow propeller, means supporting said fan inside said housing so that said propeller forces air through said gas-passages in a direction from the air inlets thereof to the air outlets thereof, said shell means comprising an outer shell and an inner shell defining boundaries of said air passages, and thermostat means in said second air passage subject to the heat of said inner shell and the air flow in said second air passage.

2. A fan-type air-heater of a type described comprising an outer tubular member and an inner tubular member radially spaced therefrom, each of said tubular members having a front end and a back end, heating means in said inner tubular member, a grill across the front end of said inner tubular member, a guard ring having an outer portion secured to the front end of said outer tubular member, the inner portion of said guard ring, said grill and said front end of said inner tubular member being secured together, said inner tubular member being shorter than said outer tubular member, heating means in said inner tubular member, said heating means comprising a pair of heating elements spirally wound of flattened heating rod, said heating elements being wound in opposite directions, a fan comprising an axial flow propeller which is smaller than said inner tubular member, and means supporting said fan with its propeller within the outline of said inner tubular member.

3. A portable air-heater of a type described comprising an outer shell having a first end and a second end, a sub-assembly secured to said first end, said sub-assembly comprising an outer guard ring, a grill, and an inner tubular metal member extending inside said outer shell but not as far as the second end of the shell, said tubular memher being spaced from said outer shell to provide an air passage, said sub-assembly having an opening at said first end for said air passage, said sub-assembly comprising a spirally wound heat ing element within said tubular member, said heating element having a pair of ends carried by said tubular member, fan means comprising an axial flow propeller, said fan being carried by said outer shell with said propeller inside said tubular member on the side of said heating element which is opposite to said grill, and a thermostat carried in said air passage for controlling said heating means.

4. A sub-assembly for an air-heater of a type described, comprising an inner metal tubular member, a grill covering an end of said tubular member, a guard ring about said grill, said grill, guard ring and tubular member having abutting end portions secured together, and a pair of 0p positely turned spiral heating elements inside said tubular member carried thereby and spaced axially thereof.

5. A sub-assembly for an air-heater of a type described, comprising an inner metal tubular member, a grill covering an end of said tubular member, a guard ring about said grill, said grill, guard ring and tubular member having abutting end portions secured together, and a pair of spiral heating elements inside said tubular member carried thereby and spaced axially thereof, each of said spiral heating elements having a pair of offset terminal ends, said terminal ends extending in the same general direction, one of said heating elements being turned with respect to the others so that said offset terminal ends lie between said spirals.

6. A sub-assembly for an air-heater of a type described comprising a metallic tubular member, a pair of spiral heating elements inside said tubular member carried thereby and spaced axially thereof, each of said spiral heating elements having a pair of ofiset terminal ends, said terminal ends extending in the same general direction, one of said heating elements being turned 180 with respect to the other so that said offset terminal ends lie between said spirals.

JOHN F. VOLKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,914,724 Johnson June 20, 1933 1,967,757 Losee July 24, 1934 1,982,190 Ball et a1 Nov. 27, 1934 2,120,795 Boothby June 14, 1938 2,456,781 Hardey Dec. 21, 1948 2,492,774 Wild Dec. 27, 1949 

